You can create an auto response from using Smart Messages.
Access Smart Messages from the Feature's page.
From the Smart Messages page you will see three tabs, Scheduled, Templates, and Auto Response. Select Auto Response. You will now see a list of any existing Auto Responses and can edit them by selecting them from the list.
Click on the + in the bottom right corner to begin a new auto response.
Type the message you would like to have as an auto response. You can use the drop down menu's to customize the Auto Response.
Click Create. You can always come back delete the auto/response. You can enable/disable the auto response within the web version of MyRepChat.